Stainless steel is a well-known alloy which is widely used to avoid corrosion. However, because of its limited hardness, it is not durable, which limits its use. If stainless steel is coated with wear-proof materials of high hardness or treated to increase its surface hardness, it will become more suitable for applications that require durability.
Conventional surface hardening techniques include gas nitriding, etc. These methods have some common disadvantages. For example, the hardened layer is too thin, and the hardness decreases rapidly with depth. Therefore, surface hardening methods for stainless steel that result in a thicker hardened layer and uniform hardness of the hardened layer are continuously being sought.
Surface hardening methods commonly used nowadays that have thicker hardened layer and uniform hardness in the hardened layer include ion nitriding and plasma nitriding. But these methods must be used in a vacuum, and consume time and energy. Therefore, research is underway for simple, quick, energy-saving and non-pollutive surface hardening methods.